Periodontal disease is a general term for a variety of dental conditions associated with either gingivitis or periodontitis. Gingivitis is an inflammation of the gingiva, or gums. It is commonly associated with poor oral hygiene and/or the hormonal state of the patient. If left untreated, gingivitis may develop into periodontitis.
Periodontitis is a bacterial disease in which the infection has progressed to involve the oral tissues that retain the teeth in the jawbone. With this disease the gums become red and inflamed. This condition, if untreated, results in damage to the ligaments and bone holding the teeth in place, and formation of pockets around the teeth. As the pockets become deeper, teeth loosen, to a point where they may fall out. Dental practitioners determine the severity of periodontitis, by measuring the depth of these pockets and reviewing x-rays of the teeth and surrounding bone.
Periodontal disease involves a different treatment protocol than other oral diseases. While many oral diseases can be treated with proper hygiene, fluoride, pastes, washes and rinses, periodontal disease is often resistant to this treatment. This is because of differences between the oral and periodontal cavities. The oral cavity is essentially an aerobic environment, constantly perfused by saliva. In contrast, the periodontal cavity is more anaerobic, and is perfused by plasma filtrate, known as “crevicular fluid”. The growth of microorganisms within the periodontal cavity microenvironment may cause periodontal disease. As the disease progresses, the periodontal microenvironment becomes more anaerobic, and the flow of crevicular fluid increases.
Efforts to treat periodontal disease have met with limited degrees of success. This is because the site of the bacterial infections in the periodontal cavity are largely inaccessible to agents present in the oral cavity as well as agents provided to the oral cavity, such as mouthwashes, rinses and the like. Moreover, the increased outflow of crevicular fluid that accompanies periodontal disease inhibits therapeutic agents placed into the oral cavity from entering the pockets.
Oral systemic administration of antibiotics has been shown to be a useful method of controlling subgingival flora in some cases. However, because of side effects, such as those of the digestive system, oral systemic administration has had only limited use in treating periodontal disease. Oral systemic therapy also requires frequent dosing; so patient compliance is frequently a problem.
Recently, efforts have focused on delivering therapeutic agents directly to these pockets, in some cases, in a controlled release formulation. In general, administration of agents directly to the pocket permits higher local drug concentrations that can be safely achieved by systemic administration. Also, some agents such as growth factors must be administered directly to the target site, i.e., the periodontal pocket. Also, as these products are typically administered by dental professionals, patient compliance is not an issue.
Administration of microparticles in dry form to the periodontal pocket by use of an apparatus has been disclosed in U.S. Pat. Nos. 5,236,355, 5,366,733 and 5,622,498, all to Brizzolara, et al., and U.S. Pat. No. 6,682,348, to Lawter, et al., the contents each of which are incorporated by reference herein. These patents disclose treating dental diseases by administration of dry microparticles to the periodontal pocket. Microparticles suitable for this purpose may have compositions, as described in U.S. Pat. Nos. 5,000,886, 5,143,661 and 5,500,228, all to Lawter, et al., all three of these patents are incorporated by reference herein, and U.S. Pat. Nos. 5,236,355, 5,366,733 and 5,622,498, all to Brizzolara, et al., and may be produced by the methods disclosed in the aforementioned six U.S. patents.
The apparatus described in the above listed patents deliver microparticles by use of a plunger to push microparticles out of a hollow cannula. The outlet of the cannula is inserted into a periodontal pocket prior to delivery of the microparticles. During administration of microparticles with such a device, there is a tendency to push the cannula outlet against tissue in the bottom of the periodontal pocket while pushing on the plunger. Tissue may block the outlet and increase the force required to push the microparticles out. At high doses of microparticles in a dry powder form, the force may be too large to easily push out the medicament, since the force required to expel a dry powder will increase rapidly with the length of the powder column. This effect may be overcome to some extent by increasing the interior diameter of the tip. However, when it is desired to deliver microparticles to a body cavity of small dimensions such as a periodontal pocket, there are limitations on the diameter of the tip. Thus, there is a need for improved devices for delivering medicaments to periodontal pockets of a human or animal. There is also a need for a device that provides the ability to administer multiple doses of a medicament.